Here's a not too horrible article written on the subject, from a IT geek perspective.
http://www.zdnet.com/world-of-spycra...ft-7000024095/
If you start thinking about things like steganography, out of band key exchange and other topics, you can understand why agencies might peruse realtime communications channels like these.
Oh, and they probably dig the elf shoes, like Tam said. But I am curious if Leroy Jenkins is really one of them?